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@PHDTHESIS{Brenner:822218,
author = {Brenner, Andreas},
othercontributors = {Häfner, Constantin and Bergs, Thomas},
title = {{S}equentielle {U}ltrakurzpuls-{L}aserbearbeitung zur
effizienten {O}berflächentexturierung; 1. {A}uflage},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Aachen},
publisher = {Apprimus Verlag},
reportid = {RWTH-2021-06602},
series = {Ergebnisse aus der Lasertechnik},
pages = {1 Online-Ressource : Illustrationen, Diagramme},
year = {2021},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, RWTH Aachen University, 2021},
abstract = {Laser structuring is becoming increasingly important in the
tool and mold making industry. In addition to design
structures (e.g. leather grain), the production of
microstructures for surface functionalization represents a
particular challenge. For example, structured surfaces
contribute to increasing the efficiency of LED-based
lighting systems or to modifying the wetting properties to
create self-cleaning surfaces. In terms of this surface
textures influence the optical and haptic properties that
are increasingly becoming a quality feature. The automotive
and consumer goods industries in particular offer a wide
range of applications for structured surfaces, which can
usually be produced by replication. The currently used
production processes for tool texturing such as
photochemical etching or laser texturing using nanosecond
lasers are limited in their precision and flexibility.
Ultrashort pulse lasers (USP) with pulse durations in the
femtosecond to picosecond range offer the possibility of
surface functionalization with highest precision and surface
quality. Due to the mainly vaporization-dominated ablation,
debris and melt-induced protrusions can be avoided in
contrast to nanosecond lasers. The main drawback is the
limited productivity with ablation rates of a few mm³/min.
Accordingly, this thesis investigates the sequential use of
ultrashort pulse laser sources for efficient surface
texturing with increased productivity. In a first step, the
possibility to increase productivity by using pulse bursts
and reducing the pulse duration from 10 ps to 2 ps is
investigated. It can be shown that the same efficiency can
be achieved as with nanosecond lasers while increasing the
surface quality by a factor of 4. In the next step, the
process of USP cleaning is investigated, which is used to
remove the oxide layer created during the productive laser
ablation. The investigation of high quality USP ablation
proves that the surface roughness can be reduced during
ablation. The final process, USP polishing, enables a final
smoothing of the roughness peaks by remelting a thin surface
layer. This technology can also be used to selectively
create specific gloss effects.The photonic USP process chain
presented here, consisting of the four individual processes
USP productive, USP cleaning, USP quality and USP polishing,
achieves time savings of up to $59\%$ compared to an
industrially established nanosecond process, while at the
same time reducing surface roughness by $92\%.$ The
component production can be carried out in one machinery
without time-consuming set-up or reclamping.},
cin = {418710},
ddc = {620},
cid = {$I:(DE-82)418710_20140620$},
typ = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
doi = {10.18154/RWTH-2021-06602},
url = {https://publications.rwth-aachen.de/record/822218},
}
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